The future importance of medical ultrasonic systems for diagnostic work has been previously noted by several task groups of the National Academy of Engineering and the National Science Foundation. These groups have made recommendations that research programs be established in several areas in order to enhance our future ultrasonic diagnostic capabilities. One of the most important areas was the development of two dimensional arrays of piezoelectric transducers for diagnostic systems. The general objective of the present study is to develop improved medical diagnostic ultrasonic systems via the development of two dimensional arrays of wide bandwidth piezoelectric transducers which are excited by wide bandwidth or pulse compressed signals. In order to accomplish the general objective a combined analytical and experimental program is proposed to investigate the laboratory performance of ultrasonic diagnostic systems which utilize two dimensional arrays of wide bandwidth transducers with various coded electrical excitations. The objectives of the analytical portion of the study are to develop an analytical foundation for the design of medical ultrasonic diagnostic systems which utilize two dimensional arrays and coded signals, and to develop general computer models which can be used for the design and evaluation of such systems. The objectives of the experimental portion of the study are to construct various wide bandwidth transducers, arrays, and systems via the use of the computer programs, and then to compare the experimental results to the analytical predictions. As a result of the experimental and analytical investigations, it is noted that wide bandwidth single element and electronically steered multielement ultrasonic diagnosis systems which utilize coded excitations will be developed and evaluated.